1. Field of the Invention
This invention relates to microwave reflector antennas. More particularly, the invention relates to a radome and shroud enclosure for reflector antennas with improved signal pattern and mechanical characteristics.
2. Description of Related Art
The open end of a reflector antenna is typically enclosed by a radome coupled to the distal end of the reflector dish and/or of a cylindrical shroud extending from the reflector dish.
The radome provides environmental protection and improves wind load characteristics of the antenna. Precision shaping may be applied to the radome to compensate for signal trajectory and/or reflection effects resulting from an impedance discontinuity introduced into the signal path of the reflector antenna by the presence of the radome. Edge(s) of the radome attachment arrangement scatter the RF signal degrading the signal pattern. Significantly, edges parallel to the signal path, such as the distal edge of a cylindrical shroud, are known to diffract signal energy present in this area, introducing undesirable backlobes into the reflector antenna signal pattern.
Prior antenna signal pattern backlobe suppression techniques include adding a backlobe suppression ring to the radome, for example via metalizing of the radome periphery as disclosed in commonly owned U.S. Pat. No. 7,138,958, titled “Reflector Antenna Radome with Backlobe Suppressor Ring and Method of Manufacturing” issued Nov. 21, 2006 to Syed et al, hereby incorporated by reference in its entirety. However, the required metalizing operations may increase manufacturing complexity and/or cost, including elaborate coupling arrangements configured to securely retain the shroud upon the reflector dish without presenting undesired reflection edges and/or extending the overall size of the radome. Further, the thin metalized ring layer applied to the periphery of the radome may be fragile, requiring increased care to avoid damage during delivery and/or installation.
The addition of a shroud to a reflector antenna improves the signal pattern generally as a function of the shroud length, but also similarly introduces significant costs as the increasing length of the shroud also increases wind loading of the reflector antenna, requiring a corresponding increase in the antenna and antenna support structure strength.
Competition in the reflector antenna market has focused attention on improving electrical performance and minimization of overall manufacturing, inventory, distribution, installation and maintenance costs. Therefore, it is an object of the invention to provide a radome and shroud enclosure for a reflector antenna that overcomes deficiencies in the prior art.